In general we use a strict subset \(\mathcal {T} \subset \mathcal {D}\)  of all labeled data points
to compute the training error (REF ). The remaining data points \(\mathcal {D} \setminus \mathcal {T}\) ,
which are not used for the training, are then used to validate the predictor learnt via (REF ) [1]}, [2]}.
